I. Field of the Invention
This invention relates to optical devices and in particular though not exclusively to optical devices housed in optical fibre connectors.
II. Related Art and Other Considerations
Optical devices housed in optical fibre connectors are frequently used in optical communications applications which require relatively inexpensive devices which in addition can be easily connected to and disconnected from an optical fibre transmission line.
The coupling efficiencies of such devices are usually rather low so that, for example, a laser having an optical output of 10 mW may couple only 50 .mu.W into the associated optical fibre. These low coupling efficiencies do not usually in themselves present a problem since in many applications even 50 .mu.W of coupled power provides ample optical power.
A problem does however arise in respect of safety, since disconnecting the fibre and its associated ferrule from the device can lead to several milliwatts of power being emitted into the environment through the fibre receptacle of the connector.
In many cases optical communications links are operated at wavelengths of 1.3 and 1.5 micrometers which presents added risks because radiation at these wavelengths is invisible.
The present invention aims to improve the safety of such optical devices incorporating optical sources having a relatively high intensity or high power output.